DIABETES TYPE 2
Type 2 diabetes mellitus was once called adult-onset diabetes. Now, because of the epidemic of obesity and inactivity in children, type 2 diabetes mellitus is occurring at younger and younger ages.
Although type 2 diabetes mellitus typically affects individuals older than 40 years, it has been diagnosed in children as young as 2 years of age who have a family history of diabetes.
Type 2 diabetes is characterized by peripheral insulin resistance with an insulin-secretory defect that varies in severity. For type 2 diabetes mellitus to develop, both defects must exist: all overweight individuals have insulin resistance, but only those with an inability to increase beta-cell production of insulin develop diabetes. In the progression from normal glucose tolerance to abnormal glucose tolerance, postprandial glucose levels first increase. Eventually, fasting hyperglycemia develops as inhibition of hepatic gluconeogenesis declines.
About 90% of patients who develop type 2 diabetes mellitus are obese. Because patients with type 2 diabetes mellitus retain the ability to secrete some endogenous insulin, those who are taking insulin generally do not develop DKA if it is stopped. Therefore, they are considered to require insulin but not to depend on insulin. Moreover, patients with type 2 diabetes mellitus often do not need treatment with oral antidiabetic medication or insulin if they lose weight or stop eating.
Maturity-onset diabetes of the young (MODY) is a form of type 2 diabetes mellitus that affects many generations in the same family with an onset in individuals younger than 25 years. Several types exist. Some of the genes responsible can be detected by using commercially available assays.
Causes
Causes
The major risk factors for type 2 diabetes mellitus are the following:
Age
Age
Older than 45 years (though, as noted above, type 2 diabetes mellitus is occurring with increasing frequency in young individuals)
Obesity
Weight greater than 120% of desirable body weight (true for approximately 90% of patients with type 2 diabetes mellitus)
Family history of type 2 diabetes in a first-degree relative (eg, parent or sibling)Hispanic, Native American, African American, Asian American, or Pacific Islander descent
History of previous impaired glucose tolerance (IGT) or impaired fasting glucose (IFG)Hypertension (>140/90 mm Hg) or dyslipidemia (high-density lipoprotein [HDL] cholesterol level <40>150 mg/dL)History of GDM or of delivering a baby with a birth weight of >9 lbPolycystic ovarian syndrome (which results in insulin resistance)
Frequency
Frequency
United States
In 2005, people with diabetes were estimated to account for 7% of the US population, or approximately 20.8 million people. Of these 20.8 million people, 14.6 million have a diagnosis of diabetes, and diabetes is undiagnosed in another 6.2 million. Approximately 10% have type 1 diabetes, and the rest have type 2. Additionally, an estimated 54 million people have pre-diabetes. Pre-diabetes, as defined by the American Diabetes Association, is that state in which blood glucose levels are higher than normal but not high enough to be diagnosed as diabetes.
In 2005, people with diabetes were estimated to account for 7% of the US population, or approximately 20.8 million people. Of these 20.8 million people, 14.6 million have a diagnosis of diabetes, and diabetes is undiagnosed in another 6.2 million. Approximately 10% have type 1 diabetes, and the rest have type 2. Additionally, an estimated 54 million people have pre-diabetes. Pre-diabetes, as defined by the American Diabetes Association, is that state in which blood glucose levels are higher than normal but not high enough to be diagnosed as diabetes.
Mortality/Morbidity
The morbidity and mortality associated with diabetes are related to the short- and long-term complications. Complications include the following:
Hypoglycemia and hyperglycemiaIncreased risk of infectionsMicrovascular complications (eg, retinopathy, nephropathy)Neuropathic complicationsMacrovascular disease (eg, coronary artery disease, stroke)Diabetes is the major cause of blindness in adults aged 20-74 years, as well as the leading cause of nontraumatic lower-extremity amputation and end-stage renal disease (ESRD).
Hypoglycemia and hyperglycemiaIncreased risk of infectionsMicrovascular complications (eg, retinopathy, nephropathy)Neuropathic complicationsMacrovascular disease (eg, coronary artery disease, stroke)Diabetes is the major cause of blindness in adults aged 20-74 years, as well as the leading cause of nontraumatic lower-extremity amputation and end-stage renal disease (ESRD).
Race
Type 2 diabetes mellitus is more prevalent among Hispanics, Native Americans, African Americans, and Asians/Pacific Islanders than in non-Hispanic whites.
Sex
The incidence is essentially equal in women and men in all populations.
Age
Type 2 diabetes mellitus is becoming increasingly common because people are living longer, and the prevalence of diabetes increases with age.It is also seen more frequently now than before in young people, in association with the rising prevalence of childhood obesity.
Although type 2 diabetes mellitus still occurs most commonly in adults aged 40 years or older, the incidence of disease is increasing more rapidly in adolescents and young adults than in other age groups.
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